Coating for metal casting molds and cores



Patented Aug. 4, 1931 UNITED STATES PATENT OFFICE MEYER L. BREED, OF NEW YORK, N. Y., ASSIGNOR TO HENRY A. GOLWYNNE, OF NEW YORK, N. Y.

COATING FOR METAL CASTING MOLDS AND CORES No Drawing.

My invention relates to improvements in coatings for the molds and cores used in pouring metal castings, and the object of the invention is to produce a coating which will enable the production of a smoother casting requiring less cleaning, and one which will be easily removed from the mold.

A further object is to devise a coating which is non-spalling and Which Will retain its bond at Very high temperatures forming a glaze for the surface of the mold or core and which will resist cutting away, also preventing fusion and penetration.

My composition consists of a mixture of a permanent binder with an anhydrous aluminum silicate (Al SiO such as sillimanite, andalusite, cyanite, topaz, dumortierite or any other anhydrous aluminum silicate which upon calcination forms mullite (3Al O 2SiO or mullite itself derived from the calcination of any of the above mentioned minerals, or produced synthetically.

I make a suspension 'of the binder and,

add thereto a small percentage of an organic oil as a temporary binder and then add the anhydrous aluminum silicate or mullite in very fine form. A paste is thus produced which can be diluted to the required coi'isistency for application to the surface of the cores and molds by either sWabbing, dipping, brushing or spraying.

The coating or wash after'being applied to the surface of the cores and molds is baked whereby such coating presents a hard surface. This hard surface prevents the cutting of sand at the gates with consequent Washing of sand into the casting.

The presence of the anhydrous aluminum silicate or mullite in the mixture is highly important. Being an exceedinglyrefractory substance with a fusion point of 3300 F. it has the property of making the protective coating resist the heat of the molten metal and prevents fusion of the metal with the sand. lVhcn molten iron or steel comes into contact with the anhydrous aluminum silicate or mullite it forms a compound that to becomes a glaze upon the surface of the Application filed "May -10, 1930. Serial No. 451,522.

mold. This glaze prevents spalling, fusion, erosion and penetration and produces smoother castings that have a better peal and shiny surfaces. It is also beneficial to add a percentage of graphite to the mix.

The coating as described is particularly helpful in casting heavy metal sections or Where there is long exposure of the mold and cores to the metal during pouring.

Although I have described my invention as particularly applicable to sand molds and cores, the coating can with equal facility be applied to permanent molds such as those constructed of metal.

W hat I claim as my invention is: 65

1. A coating for cores and molds used in casting metals consisting of anhydrous aluminum silicate and a binder.

2. A coating for cores and molds used in casting metals consisting of calcined an hydrous aluminum silicate and a binder.

3. A coating for cores and molds used in casting metals consisting of mullite and a binder.

4. A coating for cores and molds used in casting metals consisting of anhydrous aluminum silicate, a temporary binder and a permanent binder.

5. A coating for cores and molds used in casting metals consisting of calcined an- 30 hydrous aluminum silicate, a temporary binder and a permanent binder.

6. A coating for cores and molds used in casting metals consisting of mullite, a temporary binder and a permanent binder.

7. A coating for cores and molds used in casting metals consisting of anhydrous aluminum silicate, a binder and an organic oil.

8. A coating for cores and molds used in casting metals consisting of calcined anhydrous aluminum silicate, a binder and an organic oil.

9. A coating for cores and molds used in casting metals consistingpf mullite, a binder and an organic oil.

10. A coating for cores and molds used in casting metals consisting of anhydrous aluminum sllicate, a binder and graphite.

11. A coating for cores and molds used in casting metals consisting of calcined anhydrous aluminum silicate, a binder and graphite. I

12. A coating for cores and molds used in casting metals consisting of mullite, a

binder and graphite.

MEYER L. FREED. 

